Method and apparatus for generating an electric arc

ABSTRACT

A method and apparatus for reducing the gap resistance between two electrodes, such as the electrodes used fusion splicing one optical fiber to another, by injecting negative ions into the gas or gasses that are located between the electrodes. As a result, the voltage that is required to cause dielectric breakdown and initiation of the electrical arc is drastically reduced.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a continuation of U.S. Ser. No. 11/198,363,filed Aug. 5, 2005.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the generation of an electrical arc,such as may be used for cleaning and/or stripping an optical fiber orfusion splicing one optical fiber to another optical fiber.

2. Description of the Prior Art

Fiber optic cables are widely used in modern optical devices and opticalcommunications systems. Optical fibers are strands of glass fiberprocessed so that light beams transmitted through the glass fiber aresubject to total internal reflection wherein a large fraction of theincident intensity of light directed into the fiber is received at theother end of the fiber. In addition, a number of individual opticalfibers may be grouped together to form what is known as a ribbon fiber.

For some applications, the optical fiber or fibers must be manykilometers long. It is therefore often necessary to splice two shorterlengths of optical fiber (a single fiber or a ribbon fiber) together toform a longer optical fiber. The need to splice optical fibers alsoarises when it is necessary to use a length longer than can be made froma single preform, when an existing length of fiber breaks, or whenapparatus such as an amplifier is to be incorporated into a length offiber.

Optical fibers are usually coated with one or more protective layers,for example a polymer coating made of acrylate or polyimide, in order toprotect the surface of the fiber from chemical or mechanical damage. Inorder to prepare the fibers to be cleaved and spliced, or in order tofurther process the fibers to manufacture optical devices such asoptical sensors and other optical communications network components, itis necessary to remove the protective coating or coatings, a processknown as stripping, and to clean the optical fiber to remove anyremaining coating debris.

Conventional stripping methods include mechanical stripping, chemicalstripping, and thermal stripping. Mechanical stripping typicallyinvolves a stripping tool, similar to a wire stripper, which cutsthrough the coating and scrapes it off. Mechanical stripping may resultin nicks or scratches on the glass fiber surface, which could lead tocracks and degradation in the tensile strength of the fiber. Chemicalstripping uses solvents or concentrated acids to remove the polymercoating. Chemical stripping is typically very costly, presents safetyconcerns due to the nature of the chemicals that are used, and, in somecases, may adversely affect the splice strength.

Moreover, conventional cleaning methods include chemical cleaning andelectrical arc based cleaning. For example, prior art fusion splicingdevices have typically cleaned optical fibers prior to splicing in twosteps. In a first step, a chemical, typically alcohol, is used to removelarge debris (large coating particles) from the cleaved end of theoptical fiber that is left behind following the stripping step. Then, ina second step, a single electrical arc pulse, commonly referred to as a“prefuse arc,” is used to remove any small debris (smaller coatingparticles) that may remain after the chemical cleaning step. Inparticular, in this second step, the “prefuse arc” generates a plasma,and the cleaved end of the fiber is inserted into the plasma. Theintense heat of the plasma vaporizes the remaining small debris. Theprior, extra chemical cleaning step is necessary because using the“prefuse arc” and resulting plasma to remove large debris would resultin the contamination of the electrodes, v-grooves and optics of thefusion splicer due to the sputtering of the large debris.

Thus, there is a need for an improved method of stripping and/orcleaning an optical fiber prior to splicing and/or cleaving steps.

In addition, in many applications that require an arc, the voltagepotential between the electrodes is simply increased until a sparkoccurs. Once a spark occurs, the gas or gasses, such as air, between theelectrodes becomes ionized. Since ionized gasses, such as air, areconductors rather than insulators, the arc, resulting from the spark,can then be maintained easily by current regulation. Because of the factthat the gas or gasses, such as air, typically have a huge resistance tocurrent flow until dielectric breakdown and effectively a negativeresistance afterwards, highly complex and costly circuits are requiredto compensate and prevent system meltdown resulting from the relativelyhigh applied voltages. In addition, in some applications, there maybe apractical limit to the magnitude of voltage that can be applied to theelectrode. Similarly, in many applications, it is advantageous to limitthe magnitude of voltage that is required to generate an electrical arcso that smaller, less complex and less expensive electrical componentsmaybe used. Finally, a number of other factors also somewhat affect thedielectric strength of a fixed length gap between two electrodes,including humidity, pressure/altitude, gasses present, naturalradioactivity, cosmic rays, and electrode condition. To the extent thatany of these factors increase dielectric strength and gap resistance, alarger voltage will be required to generate an electrical arc betweenthe two electrodes.

Thus, there is also a need for an improved method and an improvedapparatus for generating an electrical arc, such as may be used forcleaning and/or stripping an optical fiber or fusion splicing oneoptical fiber to another optical fiber.

SUMMARY OF THE INVENTION

The present invention relates to a method of processing an opticalfiber, such as a single optical fiber or a ribbon fiber, that includesgenerating an electrical arc in a first area wherein the electrical arccreates a plasma in one or more gasses located in the first area. Theplasma that is generated is in a region referred to as the plasmaregion. The method further includes positioning a portion of the opticalfiber in a second area that is adjacent to and outside of the plasmaregion, wherein coating material that is present on the portion of theoptical fiber is removed when the plasma is present and the portion ofthe optical fiber is positioned in the second area. The positioning stepmay be performed prior to or subsequent to the arc generating step.

In one embodiment, the method is used for cleaning the optical fiber. Inthis case, the optical fiber includes at least one coating layer and theportion of the optical fiber is a stripped portion of the optical fiberformed by removing nearly all of the at least one coating layertherefrom. The coating material in this embodiment comprises coatingmaterial debris that is left on the stripped portion of the opticalfiber.

In another embodiment, the method is used for stripping the opticalfiber. In this case, the coating material comprises nearly all of the atleast one coating layer that is present at the portion of the opticalfiber that is position in the second area.

The method may also further include translating the portion of saidoptical fiber that is positioned in the second area relative to theplasma region when the plasma is present. Preferably, the translatingstep is performed at a rate of between approximately 0.1 mm/second andapproximately 100 mm/second.

The electrical arc is generated along a first axis and the optical fiberhas a longitudinal axis. The positioning step may include positioningthe optical fiber such that the longitudinal axis is generallyperpendicular to said first axis. Alternatively, the positioning stepmay include positioning the optical fiber such that the longitudinalaxis is generally parallel to the first axis.

The electrical arc may be continuous electrical arc. The electrical arcmay also be a pulsed electrical arc. Preferably, the pulsed electricalarc is generated at a frequency of about 15 KHz at a 50% duty cycle. Inaddition, the generating step may further include turning the pulsedelectrical arc on and off at a ratio separate from the primary dutycycle, wherein the ratio is selectable by a user and comprisesrepeatedly turning the pulsed electrical arc on for a first time periodand off for a second time period. For example, the first time period maybe approximately 50 ms and the second time period may one ofapproximately 150 ms, approximately 121 ms, approximately 88 ms, andapproximately 50 ms.

The one or more gasses in which the plasma is generated may include air,CO₂, or an inert gas such as nitrogen or argon. Preferably, the one ormore gasses include a gas that removes one or both of oxygen andhumidity from the first area, or a gas that reduces the dielectricstrength in the first area.

In one alternative embodiment, the method includes generating a pulsedelectrical arc in a first area, wherein the pulsed electrical arccreates a plasma in a plasma region in one or more gasses located in thefirst area. The method further includes positioning a portion of theoptical fiber at least partially within the plasma region. According tothe method, coating material that is present on the portion of theoptical fiber is removed when the plasma is present and that portion ispositioned at least partially within the plasma region. The positioningstep may be performed prior to or subsequent to the generating step. Thevarious alternative described above may also be employed in thisembodiment.

The present invention also relates to an apparatus for preparing anoptical fiber having at least one coating layer that includes strippingmodule for removing nearly all of the at least one coating layer presentat a portion of the optical fiber, a cleaning module, a cleaving modulefor cleaving an end of the optical fiber, and a fiber holding mechanismfor holding the optical fiber and moving the optical fiber among thestripping module, the cleaning module and the cleaving module. Thecleaning module includes a first electrode and a second electrode. Anelectrical arc is selectively generated in a first area between thefirst electrode and the second electrode. The electrical arc creates aplasma in one or more gasses located in the first area, wherein theplasma is located in a plasma region. In addition, the fiber holdingmechanism selectively positions the portion of the optical fiber in asecond area that is adjacent to and outside of the plasma region,wherein debris left on that portion is removed when the plasma ispresent and the portion of the optical fiber is positioned in the secondarea.

The present invention also relates to an apparatus for preparing anoptical fiber having at least one coating layer that includes strippingmodule for removing nearly all of the at least one coating layer presentat a portion of the optical fiber, a cleaning module, a cleaving modulefor cleaving an end of the optical fiber, and a fiber holding mechanismfor holding the optical fiber and moving the optical fiber among thestripping module, the cleaning module and the cleaving module. Thecleaning module includes a first electrode and a second electrode,wherein a pulsed electrical arc is selectively generated in a first areabetween the first electrode and the second electrode. The pulsedelectrical arc creates a plasma in a plasma region in one or more gasseslocated in the first area. The fiber holding mechanism selectivelypositions the portion of the optical fiber at least partially within theplasma region, wherein debris left on that portion is removed when theplasma is present and that portion is positioned at least partiallywithin the plasma region.

An aspect of the present invention also relates to a method for reducingthe gap resistance between two electrodes, such as the electrodes usedin the cleaning and stripping apparatuses described above, by injectingnegative ions into the gas or gasses that are located between theelectrodes. As a result, the voltage that is required to causedielectric breakdown and initiation of the electrical arc is drasticallyreduced.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other advantages of the present invention will become readilyapparent upon consideration of the following detailed description andattached drawings, wherein:

FIGS. 1 and 2 are front and top schematic diagrams, respectively, of acleaning apparatus according to one embodiment of the present inventionthat employs an electrical arc for removing debris from an opticalfiber;

FIG. 3 is a front schematic diagram of a cleaning apparatus that employsa pulsed electrical arc for removing debris from an optical fiberaccording to an alternative embodiment of the present invention;

FIGS. 4 and 5 are schematic diagrams of a cleaning apparatus thatemploys either a continuous electrical arc or a pulsed electrical arcfor removing debris from an optical fiber according to furtheralternative embodiments of the present invention, wherein the electricalarc creates a plasma in a gas introduced from a gas source;

FIG. 6 is a top schematic diagram of a stripping apparatus according toan alternative embodiment of the present invention that employs anelectrical arc for stripping an optical fiber;

FIG. 7 is a front schematic view of an alternative embodiment of thecleaning apparatus according to the present invention in which theoptical fiber is moveable in a direction that is generally parallel tothe axis along which the arc is generated;

FIG. 8 is a block diagram of an optical fiber prep unit according to afurther aspect of the present invention;

FIG. 9 is a schematic diagram of a cleaning apparatus that employs amethod for reducing the dielectric strength and thus the gap resistancein the area between the first electrode and the second electrodeaccording to yet a further aspect of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 and 2 are front and top schematic diagrams, respectively, of acleaning apparatus S according to one embodiment of the presentinvention that employs an electrical arc for removing debris from anoptical fiber 10. While optical fiber 10 is depicted in FIGS. 1 and 2 asa single optical fiber, it should be understood that optical fiber 10may also consist of multiple optical fibers as in the case of a ribbonfiber. As seen most readily in FIG. 2, optical fiber 10 has beenstripped, i.e., a portion of the coating layer 15 has been removedyielding an exposed glass portion 20.

Cleaning apparatus 5 includes a first electrode 25 and a secondelectrode 30. The first electrode 25 and the second electrode 30 areseparated by a fixed distance. The first electrode 25 is electricallyconnected to a power source 35. The second electrode 30 is connected toground. The power source 35 is under the control of a control unit 40that includes a processing unit such as a microprocessor. In addition,as seen in FIG. 2, a motor driven holding mechanism (not shown) isprovided to enable the optical fiber 10 to be selectively moved in thedirection of the arrows in FIG. 2. Preferably, at least the firstelectrode 25 and the second electrode 30 are provide within an enclosure(not shown), which may be a partially or fully airtight enclosure.

The power source 35 is adapted to selectively provide a voltage to thefirst electrode 25 that in turn causes an electrical arc to be generatedbetween the first electrode 25 and the second electrode 30. Theelectrical arc is created by causing a dielectric breakdown of the airbetween the first electrode 25 and the second electrode 30. Thisbreakdown occurs when a charge buildup exceeds the electrical limit ordielectric strength of the air between the first electrode 25 and thesecond electrode 30.

The voltage provided to the first electrode 25 is of such a level thatthe electrical arc that is generated creates a plasma field between thefirst electrode 25 and the second electrode 30 by ionizing the airlocated there between. As indicated by the dashed lines in FIGS. 1 and2, the region in which the generated plasma field exists is located justbelow the plane in which the optical fiber 10 is able to move. Forconvenience, this region will be referred to herein as the plasmaregion. The voltage required to create a sufficient arc for this purposeis on the order of 10 KV to 30 KV.

In one particular implementation of the embodiment of the cleaningapparatus 5 shown in FIGS. 1 and 2, the exposed glass portion 20 of theoptical fiber is positioned above and therefore outside of the plasmaregion, and a continuous arc is generated between the first electrode 25and the second electrode 30. The heat that is generated by the plasmafield far exceeds the melting temperature of the material making up thecoating layer 15. Specifically, the heat is on the order of 300° C. orhigher. As a result, rather than melting any coating layer debris, theheat actually causes a non-combustive explosion that removes any coatinglayer debris, both large and small, that is left on the exposed coreportion 20. This occurs because the coefficient of thermal expansion ofthe coating material relative to the modulus of elasticity of thecoating material is such that, when exposed to the heat generated by theplasma field, the coating martial expands at a rate that is faster thanit can accommodate without breaking up. In addition, in order for thecoating layer debris to be removed without melting or otherwise damagingthe glass material making up the exposed glass portion 20, the durationof the electrical arc must be sufficiently short and/or the opticalfiber 10, and in particular the exposed core portion 20, must betranslated relative to the plasma region at a sufficient rate.Preferably, the duration of the arc is on the order of 50 millisecondson and 100 milliseconds off, and the rate of translation is on the orderof between 0.1 mm/second and 100 mm/second, most preferably 5 mm/secondor higher. Thus, in this particular implementation of the invention, theoptical fiber 10 is positioned outside of the plasma region and the heatgenerated by the plasma field is used to remove coating debris. This isin contrast to the prior art in which, as discussed above, opticalfibers are placed directly within the plasma field generated by acontinuous electrical arc.

According to another particular implementation of the embodiment of thecleaning apparatus 5 shown in FIGS. 1 and 2, the power source 35 iscontrolled by the control unit 40 such that multiple arcs between thefirst electrode 25 and the second electrode 30 may be successivelygenerated at a particular frequency. This results in what shall bereferred to herein as a pulsed arc between the first electrode 25 andthe second electrode 30. In addition, in the preferred implementation,as the pulsed arc is generated, the optical fiber 10, and in particularthe exposed glass portion 20, is positioned above the plasma region andis translated in one or both of the directions indicated by the arrowsin FIG. 2. As the optical fiber 10 is translated, the heat generated bythe plasma field removes the coating layer debris, both large and small,that is left on the exposed core portion 20 in the manner describedabove (i.e., as a result of a non-combustive explosion), therebycleaning the optical fiber 10.

In the preferred embodiment, the pulsed arc is generated at a frequencyof about 15 KHz at a 50% duty cycle, although is should be appreciatedthat other frequencies and duty cycles may also be used withoutdeparting from the scope of the invention. The arc power that isrequired for effective cleaning will vary for each application, and willdepend on the type and quantity of optical fibers being cleanedsimultaneously. In addition, the required power level is dictated, to asmaller degree, by the environmental conditions under which the cleaningprocess is being performed (e.g., higher altitudes will require greaterpower). Finally, the required power level will be dictated by the rateat which the optical fiber 10 is translated. In the preferredembodiment, the correlation between power level and rate of translationis tested and adjustments are made automatically by the control unit 40.The arc power should thus be selectively controlled by an operatorthough the control unit 40, which, as described above, controls theoperation of the power source 35. In particular, the arc power level maybe controlled by turning the pulsed arc on and off at an adjustableratio separate from the primary duty cycle. In other words, the pulsedarc is turned on, for example at 15 KHz with a 50% duty cycle, for afirst time period, such as 50 ms, and then off for a second time period,such as 150 ms, and so on. Preferably, the arc pulsing is repeated untilthe entirety of the exposed core portion 20 is translated above theplasma field in one or both directions. In one particular embodiment,the pulsed arc is a 15 KHz 50% duty cycle arc with an on time of 50 msand an off time of 150 ms for one optical fiber, 121 ms for four opticalfibers, 88 ms for eight optical fibers, and 50 ms for twelve opticalfibers. A user interface may be provided on the control unit 40 toenable an operator to easily make the appropriate adjustments.

Referring to FIG. 3, a front schematic diagram is provided of a cleaningapparatus 5 that employs a pulsed electrical arc for removing debrisfrom an optical fiber 10 according to an alternative embodiment of thepresent invention. The apparatus and method according to this embodimentdiffer from the embodiment shown in FIGS. 1 and 2 in that in thisembodiment, the optical fiber 10 is translated at least partially, andpreferably entirely, within the plasma field that is generated by thepulsed arc between the first electrode 25 and the second electrode 30.

FIGS. 4 and 5 are schematic diagrams of a cleaning apparatus 5 thatemploys either a continuous electrical arc or a pulsed electrical arc,both as described in connection with FIG. 1 and 2, for removing debrisfrom an optical fiber 10 according to further alternative embodiments ofthe present invention. In the embodiments shown in FIGS. 4 and 5, thecleaning apparatus 5 is further provided with a gas source 45 thatstores a gas, such as CO₂ or an inert gas like nitrogen or argon. Underthe control of the control unit 40, the gas source 45 selectivelysupplies the stored gas to the region between the between the firstelectrode 25 and the second electrode 30 through nozzle 50. As a result,when the continuous or pulse arc is generated between the firstelectrode 25 and the second electrode 30, the plasma field will begenerated within the supplied gas. CO₂ is a preferred gas because itremoves both oxygen and humidity from the region where the cleaningoccurs, which in some cases may adversely effect the cleaning. Any othergas or combination of gasses that does the same thing may also be used.In addition, a gas or combination of gasses that reduces the dielectricstrength in the area between the first electrode 25 and the secondelectrode 30 may also be used. As described in greater detail elsewhereherein, reducing the dielectric strength in the area between the firstelectrode 25 and the second electrode 30 reduces the magnitude of thevoltage that must be supplied by the power source 35 to generate theelectrical arc.

The embodiment of FIG. 4 is similar to the embodiment of FIG. 1 in thatthe optical fiber 10 is positioned and translated just above the plasmaregion, and the embodiment of FIG. 5 is similar to the embodiment ofFIG. 3 in that the optical fiber 10 is translated at least partially,and preferably entirely, within the plasma region. In the embodimentsshown in FIGS. 4 and 5, the enclosure (not shown) that houses at leastthe first electrode 25 and the second electrode 30 is preferably anairtight enclosure that is operatively coupled to a vacuum pump forselectively evacuating the interior thereof before the introduction ofthe gas from the gas source 45.

As seen in FIG. 6, the various apparatus and methods described hereinmay also be used to remove a portion of the coating layer 15 of theoptical fiber 10 (i.e., to strip the optical fiber 10). In this case,the portion of the coating layer to be removed is either translatedabove (FIGS. 1, 2 and 4) or at least partially within (FIGS. 3 and 5)the plasma region generated between the first electrode 25 and thesecond electrode 30 by either the continuous arc or the pulsed arc, asthe case may be.

In FIGS. 1 through 6, the optical fiber 10 is shown as being moveable ina direction that is generally perpendicular to the axis along which thearc is generated between the first electrode 25 and the second electrode30. FIG. 7 is a front schematic view of an alternate embodiment of thecleaning apparatus 5 in which the optical fiber 10 is moveable in adirection, shown by the arrows in FIG. 7, that is generally parallel tothe axis along which the arc is generated between the first electrode 25and the second electrode 30. All other aspects of the cleaning apparatus5 may be as described above. For example, although not shown in FIG. 7,it will be appreciated that a gas source 45 may be provided as shown inFIG. 4 so that the plasma field can be generated from the gas providethereby.

FIG. 8 is a block diagram of an optical fiber prep unit 50 according toa further aspect of the present invention. The prep unit 50 includes acontrol unit 55 and a power source 60 that are similar to the control 40and power source 35, respectively, that are shown in FIG. 1 through 7.The control unit 55 and power source 60 are operatively connected to oneor more busses, represented by bus 65. The prep unit 50 also includes afiber holder 70 for holding an optical fiber while it is processed bythe prep unit 50. The fiber holder 70 is connected to electric motor 75,which in turn is operatively connected to bus 65. The motor 75 enablesthe fiber holder 70, and thus the fiber being processed, to beselectively moved within the prep unit 50 as described herein.

The prep unit 50 includes three modules that enable it to strip, cleanand cleave an optical fiber prior to being spliced (by a separate devicesuch as a fusion splicer). First, a stripping module 80 is provided forstripping the optical fiber. The stripping module 80 may employ anyknown or hereafter developed stripping methods. In one embodiment, thestripping module 80 is a mechanical stripping module having a matchingpair of flat blades and a fiber heating surface for preheating theoptical fiber prior to being stripped by the blades. In anotherembodiment, the stripping module 80 may be an electrical arc basedstripping module as shown and described in connection with FIG. 6. Inthe latter case, the prep unit 50 may include a gas source 85, similarto gas source 45 shown in FIGS. 4 and 5, for introducing a gas, such asCO₂ or an inert gas like nitrogen or argon, into the stripping module 80from which the plasma used for stripping is generated. As seen in FIG.8, both the stripping module 80 and the gas source 85 are operativelyconnected to the bus 65 in order to receive control signals from thecontrol unit 55 and/or power from the power source 60.

The prep unit 50 is further provided with an arc generated heat cleaningmodule 90 for cleaning the optical fiber after it has been stripped bystripping module 80. The arc generated heat cleaning module 90 uses aplasma generated by an electrical arc to clean the optical fiber, andmay be implemented in accordance with any of the various embodimentsdescribed herein in connection with FIGS. 1, 2, 3, 4, 5 and 7. A highvoltage source 95, operatively coupled to the power source 60 throughthe bus 65, is connected to arc generated heat cleaning module 90 forproviding the high voltages necessary to create the continuous or pulsedelectrical arc. In addition, as will be appreciated, gas source 85 isconnected to arc generated heat cleaning module 90 for embodiments inwhich a gas such as CO₂ or an inert gas like nitrogen or argon is usedin the generation of the plasma.

Finally, prep unit 50 includes a cleaving module 100 for cleaving thestripped and cleaned end of the optical fiber. The cleaving module 100may employ any known or hereafter developed cleaving methods. Forexample, the cleaving module 100 may include a straight diamond edge forultrasonically cleaving the optical fiber. This solution, which resultsin a low cleave angle, is particularly well adapted for use inconnection with single fibers, but is not well suited for ribbon fibers.Alternatively, the cleaving module 100 may use a carbide blade to scribethe optical fiber and a plunger mechanism to break the fiber at thescribe point and create a flat cleave. This solution may be used withboth single fibers and ribbon fibers.

In operation, an optical fiber that is to be spliced is placed on fiberholder 70. The fiber holder 70 is then moved by motor 75 to thestripping module 80 where an appropriate amount of protective coatinglayer is removed. Next, the fiber holder 70 is moved by the motor 75 tothe arc generated heat cleaning module 90 wherein the debris remainingafter the cleaning step is removed using electrical arc based cleaningas described herein. Finally, the fiber holder 70 is moved by motor 75to the cleaving module 100 wherein the optical fiber that is to bespliced is cleaved so that it may subsequently be spliced with anotherfiber.

As described above, the various embodiments of the present inventionutilize an electrical arc generated between two electrodes (the firstelectrode 25 and the second electrode 30) separated by a certain fixeddistance to create a plasma in a gas or mixture of gasses locatedbetween the electrodes. The electrical arc is created by applying avoltage to one of the electrodes (the first electrode 25) that issufficient to cause a dielectric breakdown of the gas or mixture ofgasses present between the two electrodes. This breakdown occurs when acharge buildup exceeds the electrical limit or dielectric strength ofthe air between the electrodes. Thus, the magnitude of the voltage thatis required to cause the dielectric breakdown and thus generate theelectrical arc is a function of the dielectric strength of the gas ormixture of gases present between the two electrodes. The higher thedielectric strength, and thus the higher the gap resistance between thetwo electrodes, the larger the voltage that is required to generate theelectrical arc.

As described in the Background, in many applications that require anarc, the voltage potential between the electrodes is simply increaseduntil a spark occurs. Once a spark occurs, the gas or gasses, such asair, between the electrodes becomes ionized. Since ionized gasses, suchas air, are conductors rather than insulators, the arc, resulting fromthe spark, can then be maintained easily by current regulation. Becauseof the fact that the gas or gasses, such as air, typically have a hugeresistance to current flow until dielectric breakdown and effectively anegative resistance afterwards, highly complex and costly circuits arerequired to compensate and prevent system meltdown resulting from therelatively high applied voltages. In addition, in some applications,there may be a practical limit to the magnitude of voltage that can beapplied to the electrode. Similarly, in many applications, it isadvantageous to limit the magnitude of voltage that is required togenerate an electrical arc so that smaller, less complex and lessexpensive electrical components may be used. Finally, a number of otherfactors also somewhat affect the dielectric strength of a fixed lengthgap between two electrodes, including humidity, pressure/altitude,gasses present, natural radioactivity, cosmic rays, and electrodecondition. To the extent that any of these factors increase dielectricstrength and gap resistance, a larger voltage will be required togenerate an electrical arc between the two electrodes.

Thus, an aspect of the present invention provides a method by which thegap resistance between two electrodes separated by a fixed distance canbe reduced, thereby reducing the magnitude of the voltage that isrequired to generate an electrical arc between the two electrodes. Inparticular, the present invention reduces the gap resistance between twoelectrodes by injecting negative ions into the gas or gasses that arelocated between the electrodes. As a result, the voltage that isrequired to cause dielectric breakdown and initiation of the electricalarc is drastically reduced. This minimizes the impact of uncontrolledvariables (listed above) while simultaneously decreasing the magnitudeof the current avalanche caused when dielectric breakdown occurs.

FIG. 9 is a schematic diagram of a cleaning apparatus 5 that employseither a continuous electrical arc or a pulsed electrical arc, both asdescribed in connection with FIGS. 1 and 2, for removing debris from anoptical fiber 10 according to a further alternative embodiment of thepresent invention. .The embodiment of cleaning apparatus 5 shown in FIG.9 employs the method described above for reducing the dielectricstrength and thus the gap resistance in the area between the firstelectrode 25 and the second electrode 30. The cleaning apparatus 5 shownin FIG. 9 is further provided with an ionizer device 105 in closeproximity to the first electrode 25 and the second electrode 30. Underthe control of the control unit 40, the ionizer device 105 injectsnegative ions into the region between the first electrode 25 and thesecond electrode 30, and thus into the gas, which in this particularcase is air, that is located in that region. In the embodiment shown inFIG. 9, the ionizer device 105 is a standard negative ionizer circuit110 electrically coupled to an associated electrode 115, such as thosethat are employed in well known air cleaning devices. In such a case,when the ionizer circuit 110 is turned on, the associated electrode 115emanates negative ions into the air. As will be appreciated, other knownionizer device configurations may also be employed. The presence ofthese additional ions between the first electrode 25 and the secondelectrode 30 greatly reduces the dielectric strength of the gas, andtherefore the gap resistance between the first electrode 25 and thesecond electrode 30. Since ionized air is a good conductor ofelectricity, an electrical arc can easily be created in this mediumwithout significant consideration of the variables mentioned above andwith significantly reduced voltages. In combination, these advantageslead to a more stable and controllable arc with simpler and more costeffective circuitry. It is important to note that the ionizer electrodeshould not be positioned too close to the first electrode 25 and thesecond electrode 30 as an electrical discharge between them is notdesirable.

As will be appreciated, the ionizer device 105, and thus the methoddescribed above, may be used in connection with any of the variousembodiments described herein (FIGS. 3 through 7) to reduce the voltagethat must be provided by power source 35 to generate an electrical arc.In the embodiments that utilize a gas source 45 (FIGS. 4 and 5), thenegative ions are injected into the gas or gasses that are introduced bythe gas source 45.

As will be also appreciated, the method of reducing dielectric strengthand gap resistance is not limited to use with the cleaning apparatus andstripping apparatus embodiments described herein. Instead, it may beused in any application that requires the generation of an electricalarc between two electrodes. For example, in the arena of fusionsplicing, an electrical arc is utilized to generate sufficient heat tomelt and subsequently bond together two silica glass optical fibers. Anionizer device, such as ionizer device 105, may be provided in such anapplication to inject negative ions into the region between the arcgenerating electrodes such that the voltage that is required to generatethe arc used in the fusion splicing process may be reduced. Otherpotential applications will be apparent to those of skill in the art,such as, without limitation, in the arc welding and arc lighting fields.

In many applications, it is advantageous to be able to selectivelycontrol the location and orientation of, i.e., move, a plasma field thatis generated by an electrical arc between two electrodes. For example,in the case of fusion splicing of optical fibers using a plasma, theability to anneal the splice point where the fiber ends have been fusedtogether by sweeping the plasma field (e.g., in a left to right fashion)is advantageous as it improves the quality of the splice. According to afurther aspect of the present invention, an ionizer device, such asionizer device 105, may be used to control and selectively move andadjust a plasma field generated between two electrodes. In particular,because an ionizer device as described herein emits negative ions, itbehaves in a manner similar to a magnet and is able to pull the plasmafield toward it. In the case of the ionizer device 105, the electrode115 emits the negative ions and therefore has a negative potential. Byadjusting the power output (which controls the number of negative ionsemitted), the location, and/or the orientation (relative to the arcpath; i.e., the degree to which it points in the direction of the arcpath) of the ionizer electrode 115, the plasma field generated as aresult of the arc can be selectively moved and repositioned (i.e.,steered) relative to its original path. This feature can be valuablebecause it gives a new dimension of control to the arc and resultingplasma field that is currently unavailable in the industry.

While preferred embodiments of the invention have been described andillustrated above, it should be understood that these are exemplary ofthe invention and are not to be considered as limiting. Additions,deletions, substitutions, and other modifications can be made withoutdeparting from the spirit or scope of the present invention.Accordingly, the invention is not to be considered as limited by theforegoing description but is only limited by the scope of the claimsthat ultimately issue.

1. A method of generating an electrical arc, comprising: providing afirst electrode and a second electrode; injecting a controlled number ofions into a gap region between said first electrode and said secondelectrode by causing an ionizer device located in proximity to saidfirst electrode and said second electrode to emit said controlled numberof ions by adjusting a power of said ionizer device, wherein said powerdetermines said controlled number, said controlled number of ionsreducing a gap resistance of said gap region; and providing a voltage tosaid first electrode, said voltage causing said electrical arc to beformed between said first electrode and said second electrode.
 2. Themethod according to claim 1, wherein said gap region includes air andwherein said controlled number of ions is injected into said air.
 3. Themethod according to claim 1, wherein said gap region includes one ormore gasses and wherein said controlled number of ions is injected intosaid one or more gasses.
 4. The method according to claim 1, whereinsaid step of injecting said controlled number of ions into said gapregion occurs prior to said step of providing said voltage.
 5. Themethod according to claim 4, wherein said step of injecting saidcontrolled number of ions into said gap region also occurs during saidstep of providing said voltage.
 6. The method according to claim 5,wherein said electrical arc creates a plasma in one or more gasseslocated in said gap region, the method further comprising selectivelymoving and repositioning said plasma by selectively controlling one ormore of a location from which said controlled number of ions isinjected, an orientation relative to said plasma from which saidcontrolled number of ions is injected, and a level of the power levelused to generate said controlled number of ions.
 7. The method accordingto claim 1, wherein said step of injecting said controlled number ofions into said gap region occurs during said step of providing saidvoltage.
 8. The method according to claim 7, wherein said electrical arccreates a plasma in one or more gasses located in said gap region, themethod further comprising selectively moving and repositioning saidplasma by selectively controlling one or more of a location from whichsaid controlled number of ions is injected, an orientation relative tosaid plasma from which said controlled number of ions is injected, and alevel of the power used to generate said controlled number of ions. 9.The method according to claim 1, wherein said electrical arc creates aplasma in one or more gasses located in said gap region, the methodfurther comprising selectively moving and repositioning said plasma byselectively controlling one or both of a location from which saidcontrolled number of ions is injected and an orientation relative tosaid plasma from which said controlled number of ions is injected.
 10. Amethod of fusion splicing a first optical fiber to a second opticalfiber, comprising: providing a first electrode and a second electrode;injecting ions into a gap region between said first electrode and saidsecond electrode, said ions reducing a gap resistance of said gapregion; providing a voltage to said first electrode, said voltagecausing an electrical arc to be formed between said first electrode andsaid second electrode, said electrical arc generating heat; and usingsaid heat to melt a portion of said first optical fiber and a portion ofsaid second optical fiber to cause said first optical fiber to be bondedto said second optical fiber.
 11. The method according to claim 10,wherein said step of injecting said ions into said gap region occursprior to said step of providing said voltage.
 12. The method accordingto claim 11, wherein said step of injecting said ions into said gapregion also occurs during said step of providing said voltage.
 13. Themethod according to claim 10, wherein said step of injecting ions into agap region between said first electrode and said second electrodecomprises injecting a controlled number of ions into a gap regionbetween said first electrode and said second electrode.
 14. The methodaccording to claim 13, wherein said step of injecting a controllednumber of ions into a gap region between said first electrode and saidsecond electrode comprises causing an ionizer device located inproximity to said first electrode and said second electrode to emit saidcontrolled number of ions by adjusting a power of said ionizer device,wherein said power determines said controlled number.
 15. An apparatusemploying an electrical arc, comprising: a first electrode and a secondelectrode; an ionizer device for injecting a controlled number of ionsinto a gap region between said first electrode and said secondelectrode, wherein said ionizer device is located in proximity to saidfirst electrode and said second electrode and is caused to emit saidcontrolled number of ions by adjusting a power of said ionizer device,wherein said power determines said controlled number, said controllednumber of ions reducing a gap resistance of said gap region; and avoltage source for providing a voltage to said first electrode, saidvoltage causing said electrical arc to be formed between said firstelectrode and said second electrode.
 16. The apparatus according toclaim 15, wherein said apparatus is an apparatus for fusion splicing afirst optical fiber to a second optical fiber, wherein said electricalarc generates heat, and wherein said apparatus further comprises a fiberholding mechanism for holding said first optical fiber and said secondoptical fiber in a position wherein said heat is used to melt a portionof said first optical fiber and a portion of said second optical fiberto cause said first optical fiber to be bonded to said second opticalfiber.
 17. The apparatus according to claim 15, wherein said ionizerdevice includes an ionizer circuit and a third electrode.
 18. Theapparatus according to claim 15, wherein said electrical arc creates aplasma in one or more gasses located in said gap region, wherein saidplasma may be selectively moved and repositioned using said ionizerdevice.
 19. The apparatus according to claim 18, wherein said plasma isselectively moved and repositioned using said ionizer device byselectively controlling one or more of a location of said ionizerdevice, an orientation of said ionizer device relative to said plasma,and a power level used by said ionizer device to generate said ions. 20.The apparatus according to claim 16, wherein said electrical arc createsa plasma in one or more gasses located in said gap region, wherein saidplasma may be selectively moved and repositioned using said ionizerdevice.
 21. The apparatus according to claim 20, wherein said plasma isselectively moved and repositioned using said ionizer device byselectively controlling one or more of a location of said ionizerdevice, an orientation of said ionizer device relative to said plasma,and a power level used by said ionizer device to generate said ions. 22.The apparatus according to claim 15, wherein said apparatus is anapparatus for preparing an optical fiber, wherein said electrical arcgenerates heat, and wherein said apparatus further comprises a fiberholding mechanism for holding said optical fiber in a position whereinsaid heat is used to remove coating material that is present on aportion of said optical fiber.
 23. The apparatus according to claim 22,wherein said optical fiber includes at least one coating layer, whereinsaid preparing comprises cleaning said optical fiber, wherein saidportion of said optical fiber is a stripped portion of said opticalfiber formed by removing nearly all of said at least one coating layerfrom said portion of said optical fiber, and wherein said coatingmaterial comprises debris left on said stripped portion of said opticalfiber after said nearly all of said at least one coating layer isremoved from said portion of said optical fiber.
 24. The apparatusaccording to claim 22, wherein said optical fiber includes at least onecoating layer, wherein said preparing comprises stripping said opticalfiber, and wherein said coating material that is present on said portionof said optical fiber that is removed comprises nearly all of said atleast one coating layer that is present at said portion of said opticalfiber.
 25. The apparatus according to claim 18, wherein said plasma isselectively moved and repositioned using said ionizer device byselectively controlling one or both of a location of said ionizer deviceand an orientation of said ionizer device relative to said plasma.